Microbolometer structures are generally fabricated on monolithic silicon substrates to form an array of microbolometers, with each microbolometer functioning as a pixel to produce a two-dimensional image. The change in resistance of each microbolometer is translated into a time-multiplexed electrical signal by circuitry known as read out integrated circuit (ROIC). The combination of ROIC and the microbolometer array are commonly known as a microbolometer focal plane array (FPA). Additional details regarding microbolometers may be found, for example, in U.S. Pat. Nos. 5,756,999 and 6,028,309, which are herein incorporated by reference in their entirety.
Each microbolometer in the array is generally formed with two separate contacts, which are not shared with adjacent microbolometers in the array. One contact is used to provide a reference voltage for the microbolometer while the other contact provides a signal path from the microbolometer to the ROIC. A drawback of having two contacts per microbolometer is that the contacts do not scale proportionally as semiconductor processing technologies transition to smaller dimensions. Consequently, as microbolometer dimensions are reduced, the contacts consume a greater percentage of the area designated for the microbolometer, which reduces the area available for the desired resistive portion of the microbolometer and impacts microbolometer performance.
For conventional approaches that implement shared contacts within a microbolometer array, there may be some susceptibility to column-to-column short defects. For example, if a column-to-column short defect occurs, the data from the microbolometers (microbolometer read outs) within the columns associated with the column-to-column short defect may exhibit high noise and crosstalk.
As a result, there is a need for improved techniques for implementing microbolometer focal plane arrays.